The invention relates to an air filter device for an internal-combustion engine of the type including a charge-air compressor, a charge-air cooler, a water-air heat exchanger and a motor-driven blower with a blower hood.
Filter devices which, apart from a dry air filter, are further provided with an upstream dust precipitator or preliminary cyclone precipitator are customary in vehicle operation attended by heavy dust loading.
German Patent Document No. 2,738,293 discloses such an air filter device in which a centrifugal dust precipitator with a dust extraction blower is arranged in a dust exhaust-air line upstream of a dry air filter, in order to ensure dust-free and low-wear operation.
In the case when trouble-free operation of the extraction blower is impaired, or the operation of the extraction blower even fails in the event of a drive defect, the dry air filter, which is usually constructed as a fine filter, can become choked, with the result that the internal-combustion engine stalls because of lack of air.
Moreover, in the case of supercharged internal-combustion engines, severe wear on the charge-air compressor and blockage of the air ducts in the charge-air cooler can occur.
It is an object of the invention to take measures on an air-filter device of the type referred to above by means of which even in the event of a functional impairment or even failure of the dust extraction blower reliable operation remains guaranteed for the internal-combustion engine even in the case of supercharged internal-combustion engines.
This object is achieved according to preferred embodiments by providing a filter arrangement comprising:
a dust precipitator and a dry air filter in an intake line leading to the internal-combustion engine,
a dust extraction blower in a dust exhaust-air line connected to the dust precipitator,
an additional exhaust-air line in addition to the dust exhaust-air line which is connected to an intake side of the motor-driven blower, and
a shut-off element in the additional exhaust-air line which opens in the event of failure of the dust extraction blower.
The measures according to the invention continue to enable adequate removal of dust even in the event of a defect in the extraction blower, so that driving operation can be maintained without the risk of choking in the intake section of the internal-combustion engine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.